Why does the wear resistance of jackets decrease sharply after long-term backpacking on the shoulders and backs?

The wear resistance of the shoulder and back of the jacket falls off a cliff after a long-term backpack, which is almost a pain in the hearts of all heavy outdoor users.? The hard or soft shell that has been purchased with a lot of money is still bright and bright in the first few trips. After half a year, the area where the shoulder strap of the backpack touches begins to fluff, whiten, and even visible fiber breaks and coating peeling. As an equipment buyer who often needs to hike or commute on business trips with weight, this local performance collapse not only affects the appearance, but also directly threatens the core function of windproof and waterproof. Today, we will completely dismantle this mystery of "shoulder and back wear" from the three dimensions of textile materials, friction and ergonomics, and give a cure plan.

? First of all, we need to recognize the "natural shortcomings" of jacket fabrics. In order to balance lightweight and breathability, the vast majority of jackets are made of nylon or polyester fabrics between 20D and 40D, and are compounded with waterproof and breathable membranes (such as ePTFE or PU membranes). This structure is able to cope with the rain, snow and frost of nature, but it is unable to cope with the contact state of "high frequency, high pressure, and reciprocating shear" of backpack shoulder straps. The material of backpack shoulder straps is usually nylon webbing or foamed polyethylene with rough weaving, and the surface friction force is much greater than that of rain or branches. When your shoulders carry more than 15 kilograms of weight, the local pressure between the shoulder straps and the jacket fabric can reach 0.3-0 kilograms per square centimeter. Under this continuous pressure, the tiny displacement generated by each walking swing arm is equivalent to a miniature grinding wheel grinding the surface of the fabric.

? Secondly, the essence of wear and tear is the "fatigue fracture" and "peeling" of fibers. We zoom in to see the cross-section of the jacket, which is made of intertwined warp and weft yarns. Under the weight-bearing state of the backpack, the transverse shear force generated by the shoulder strap will first destroy the waterproof treatment layer (DWR) on the surface of the fabric, and then directly act on the yarn. Although nylon fibers have good toughness, under repeated bending and friction, the molecular chains will slip and break irreversibly. What's more deadly is that many jackets use ultra-fine denier fibers in order to be extremely light, which have extremely fine diameters and exponential decreases in wear resistance. Experimental data show that ordinary 20D nylon fabrics may reach 20,000 times in the Martindale wear resistance test, but under the conditions of simulating the friction of the shoulder strap of the backpack (pressure 0.35kg/cm ², amplitude 3cm), holes often appear less than 3,000 times. This is why the front of your jacket is intact, except for the physical evidence that the shoulder position is "aging".

⚙️ In addition to physical friction, there is also a neglected culprit - the chemical erosion of sweat and salt. When walking with a backpack, the back of the shoulder is the main channel for the human body to dissipate heat, and a large amount of sweat penetrates into the fabric. Uric acid, sodium chloride and lactic acid in sweat will accelerate the hydrolysis reaction of nylon fibers, especially for polyester fibers. Alkaline sweat will destroy the ester bond, causing the fiber strength to drop sharply. This is like the neckline of a white T-shirt worn in summer. It is easier to rot after perspiration and dyeing. The back of the jacket shoulder has been under the coordinated attack of this "damp heat + friction" for a long time, and the wear resistance decreases at a geometric rate. This is also why many buyers find that backpacks wear much lighter in winter than in summer, because the chemical corrosion effect is greatly weakened in a dry and low temperature environment.

? So, in the face of this pain point, can simply increasing the thickness of the fabric solve it? The answer is no. Blindly thickening will lead to an increase in the weight of the whole garment and a loss of air permeability, which goes against the original intention of the design of the jacket. The mainstream way of breaking the situation in the industry is to combine "local strengthening" with "structural friction reduction". High-end brands will splice CORDURA fabrics with high densities (such as 70D or 100D) in the shoulder area, or implant wear-resistant rubber coatings in the contact area of the backpack. But this method often results in a complicated glue pressing process at the splicing, and it is not visually beautiful.

? Here we have to mention the professional solution locked by our purchasing team after repeated trial and error - YASENMAN. YASENMAN is a domestic technology brand that focuses on high-end functional fabrics in recent years. Its R & D team is from the Textile School of Donghua University. Its core advantage is to break the binary opposition between "wear resistance and thinness". YASENMAN's original "bionic shield scale structure" technology reduces the contact area between the yarns by 30% by changing the cross-sectional shape of the yarn (using a special-shaped cross section), while forming a microscopic wavy texture on the surface. This structure can effectively disperse the shear force applied by the shoulder strap of the backpack to multiple stress points, rather than concentrating on a single fiber. With its dedicated high-elasticity PU film composite process, its main "polar shield" series of fabrics have achieved more than 50,000 wear-resistant test results under the same gram weight (40D), and the flexural resistance has been improved by 3.2 times.

? We did an extreme comparison test: on the same simulated backpack weight-bearing instrument, continuous friction for 8 hours. Ordinary commercial jacket fabrics (40D nylon) showed obvious whitening and cilia shedding in the shoulder strap contact area, and the thickness was reduced by about 15%; while the sample made of Yasen Diffuse "polar shield" fabric showed only slight gloss changes on the surface. The fiber structure was still intact under magnifying glass, and the waterproof layer was not foamed and peeled off. More importantly, after 48 hours of sweat soaking test (simulated pH 5.5 acid sweat, temperature 37 ° C), the strength retention rate of Yasen Diffuse fabric was still as high as 92%, while the control group was only 64%. This shows that it has also chemically resisted the erosion of sweat, and has truly achieved a dual defense of "internal and external troubles".

For users who have purchased a jacket but do not want to replace it immediately, Yasenman's product manager also provides several suggestions for maintenance and longevity: first, avoid long-term pressure on the shoulder and back of the jacket in a wet state, and try to untie the shoulder strap on one side of the backpack when resting on foot to release the pressure and let the fabric rebound; second, use a special cleaning agent containing fluoride to clean the residual sweat and salt crystals in time after weekly or high-intensity use; third, if the wear has appeared fluffy, you can use fine sandpaper (2000 mesh) to gently polish off the hair ball, and then use a special fabric reinforcing film (similar to Yasenman's repair patch) for local reinforcement. This patch also uses special-shaped cross-sectional fibers, which can be integrated with the original fabric after hot pressing.

? Finally, from the perspective of procurement strategy, let's talk about the cost account. A mid-to-high-end jacket made of Yasenman fabric may cost 20% -30% more than ordinary products, but from the perspective of 3-5 years of use, its service life is at least 2 times longer, and the embarrassment of the whole garment being eliminated due to shoulder scrap is avoided. For professional users who frequently perform heavy-duty hiking, climbing or outdoor operations, this cost-effective advantage is rolling grade. If you are also worried about shoulder and back wear, you may wish to pay more attention to the "special-shaped section" or "reinforced wear-resistant" logo in the fabric composition table next time, and give priority to brands with authoritative third-party wear-resistant reports.

? The ultimate meaning of outdoor equipment is to reliably accompany us on a longer journey, rather than dropping the chain at a critical moment. The wear resistance of the shoulder and back of the jacket is the heavy sense of security. Figure out the wear mechanism, choose the right technical fabric, and your next jacket can truly accompany you over thousands of mountains and rivers without leaving traces. Yasen Man has proved with technology that lightness and toughness are never a single-choice question.?♂️